psi assumption

"...psi is a statistically significant departure of results from those
expected by chance under circumstances that mimic exchanges of information
between living organisms and their environment, provided that (a) proper statistical models and
methods are used to evaluate the significance, and (b) reasonable
precautions have been taken to eliminate sensory cues and other
experimental artifacts." --John
Palmer (1983)

"The
term psi denotes anomalous processes of information or energy transfer,
processes such as telepathy or other forms of extrasensory perception that
are currently unexplained in terms of known physical or biological
mechanisms. The term is purely descriptive: It neither implies that such
anomalous phenomena are paranormal nor connotes anything about their
underlying mechanisms." --Daryl
J. Bem and Charles Honorton*

"Parapsychologists have no positive theory or model of the phenomena they claim to be studying. What they call “psi” is defined and identified negatively. They claim having demonstrated the existence of “psi” whenever they obtain a statistically significant result which cannot be readily explained by mundane causes. This strategy has many undesirable problems from a scientific perspective. For one thing, it is impossible to discover every possible normal cause in a particular experiment. For another, this allows them to claim any departure from chance as evidence for psi." --Ray Hyman*

The psi assumption is the assumption
that any significant departure from the laws of chance in a test of
psychic ability is evidence that something
anomalous or
paranormal has occurred.

The psi assumption has been made by many
parapsychologists since the scientific
investigation of psychic phenomena began in earnest with the establishment
of the Society for Psychical Research in
1882. In the first scientific test of psychic power done for the society,
Sir William Fletcher Barrett, a professor of physics at the Royal College of
Science in Dublin, declared that he had evidence that the subjects of his
study gave evidence of paranormal abilities because they could perform at
guessing games significantly better than chance would predict. He did a number of
experiments with the Creery sisters and their servant girl and came away declaring that the odds of
their being able to guess correctly in one experiment “were over a million
to one.” The odds of their guessing correctly five cards in row were “over
142 million to one” and guessing correctly eight consecutive names in a row
were “incalculably greater” (Christopher 1970: 10). Of course, we now know
the girls were able to do so well in the games because they were cheating.
However, we should not make the mistake of thinking that there are only two
possibilities when amazing feats at guessing games are achieved. Even if
such subjects are not cheating, it does not follow that they are using
psychic abilities.

Many of J. B. Rhine's experiments involved
using a specially designed deck of cards developed by one of his assistants
named Zener. A deck consists of 25 cards with 5
cards each of a star, three vertical wavy lines, a plus sign, a circle, and
a square. If a subject correctly named 5 out of the shuffled deck of 25 ESP
cards, it was considered pure chance. Certain subjects consistently named 6
out of 25 cards correctly. Rhine and his associates concluded that this
departure from chance expectancy demonstrated the existence of
ESP. He even concluded that subjects who consistently
named 4 out of 25 cards also showed psychic ability. He called it
psi missing and attributed it to the subject’s
negative attitude toward both him and the paranormal. It is possible some of
Rhine's subjects were cheating. We know that some of the decks of cards he
used were transparent, allowing receivers to see what card the sender was
looking at. It is also possible that the distribution of subjects who scored
above, below, and at chance levels is exactly what would be predicted by the
laws of probability.

Another example of the psi assumption
can be found in the work of S. G. Soal (1889-1975), a mathematician at Queen
Mary College, London University, who aimed to improve on Rhine’s rather
sloppy methods by systematically excluding what
sensory
leakage (non-telepathic communication) and deception of any kind in his ESP
experiments. By 1939 he had tested over 160 subjects for ESP in more than
128,000 guessing trials. He found no evidence of telepathy. Actually, what
he found was nothing of statistical interest. That is, he found nothing of
statistical interest until he went data mining for
displacement. Soal found statistically
significant numbers with two of his 160 subjects when he correlated guesses
with cards preceding or following the target cards. He and others took this
as evidence of clairvoyance. We now know that
Soal didn’t go data mining. He went data changing (Hansel 1989: 111-116).

In any case, in addition to the problems of cheating by subjects and fraud
by experimenters, there are two other kinds of problems with the psi assumption, one logical and one
methodological. From a logical point of view, parapsychologists are either begging the question
(assuming what they should be proving)
or they are committing the fallacy of
affirming the consequent. (If
it’s psi, then the data deviate from chance. The data deviate from chance.
So, it’s psi. Or, if a person is psychic, then that person will do
better than chance in guessing experiments. That person did better than
chance in a guessing experiment. Therefore, that person is psychic.)

The assumption is also questionable on methodological grounds. There is
no reason to believe that the laws of probability, which are purely formal
and ideal, should apply directly to any finite set of events. It may be true
that the odds of a coin coming up heads or tails is 1 in 2, but that gives
us no information as to what will happen in the real world for any given
number of tosses. Ideally, in a large number of tosses, heads should come up
50% of the time. In the real world, there is no way to know exactly how many
times heads will come up in, say, ten million tosses. We can be pretty sure the
number will be very close to five million (assuming a fair coin and a fair
toss), but we cannot know a priori exactly how
many times heads will come up.

Studies comparing random strings with random strings, to simulate
guessing numbers or cards, have found
significant departures from what would be expected theoretically by chance
(Alcock 1981: 159). For example, Harvie “selected 50,000 digits from various
sources of random numbers and used them to represent “target cards” in an
ESP experiment. Instead of having subjects make
guesses, a series of 50,000 random numbers were produced by a computer.” He
found a hit rate that was significantly less than what would be predicted by
chance (Alcock 1981: 158-159).

In the 1930s, Walter Pitkin of Columbia University printed up
200,000 cards, half red and half blue, with 40,000 of each of the five
ESP card symbols. The cards were mechanically
shuffled and read by a machine. The result was two lists of 100,000 randomly
selected symbols. One list would represent chance distribution of the
symbols and the other would represent chance guessing of the symbols.
However, the actual matches and what would be predicted by accepted odds
didn’t match up. The total number was 2% under mathematical expectancy. Runs
of 5 matching pairs were 25% under and runs of 7 were 59% greater than
mathematical expectancy (Christopher 1970: 27-28). The point is not whether
these runs are typical in a real world of real randomness or whether they
represent some peculiarity of the shuffling machine or some other quirk. The
point is that it is not justified to assume that statistical probability
based on true randomness and a very large number of instances applies
without further consideration to any finite operation in the real world such
as guessing symbols in decks of 25 cards shuffled who knows how or
how often, or rolling dice, or trying to affect a random number generator
with one's mind. As Alcock put it: “If such significant variation can be
produced by comparing random strings with random strings, then the
assumption that any significant variation from chance is due to psi seems
untenable (Alcock 1981: 158-159).”

The defender of psi might well ask: Why do some people perform better
than chance in some experiments? We know some do better because they cheat.
Some cheaters have admitted their cheating. Of course, it is possible that
the Creery sisters and others who have admitted to cheating were lying about
it but that seems farfetched. Of some others we might say we don't know for
sure, but we have good reason to believe they cheated. For example,
Hubert Pearce, Jr., one of J. B. Rhine's psychic stars, performed
exceptionally well in card guessing experiments. In nearly 700 runs of the
ESP cards, he averaged approximately 32% success vs. a chance expectation of
20%. But when Rhine used a magician to observe Pearce, he performed at
chance levels. “There are at least a dozen ways a subject who wished to
cheat under the condition Rhine described could deceive the investigator”
(Christopher 1970: 24-25). Rather than admit that when controls are
tightened it becomes more difficult to be deceived, many psi researchers
have concluded that the controls interfere with psychic power by destroying
the trust that is necessary for psychic powers to work. Critics consider
this an ad hoc hypothesis.

But, as we noted above, we cannot justifiably assume that all the Pearces
in the psychic world have cheated. So, what other explanation, besides
actually having psychic powers, could explain the ability of some people to
do significantly better than chance in guessing experiments?

Before attempting to offer some alternative explanations, I should first
note that there is no way I, or anyone else, could know why each and every
individual who performs better than chance in a given experiment did so. I
should also note that I take it for granted that if a person has psychic
abilities then that person should do significantly better than chance in
guessing exercises. I should also note
clairvoyance or telepathymay be the
reason why some people do significantly better than chance in guessing
experiments. And psychokinesismay be the
reason why some people are able to appear to affect the output of random
number generators (RNGs). Finally, I should note that if every possible
explanation except psi has been shown to be false or highly improbable, it
would be reasonable to conclude that psi is the best explanation for results
that deviate significantly from chance in guessing or RNG experiments.

other possible explanations

Here are just a few possible explanations for data
indicating significantly greater than chance results in psi experiments:
selective reporting, poor experimental design, inadequate number of
individuals in the study, inadequate number of trials in the experiment,
inadequate number of experiments (e.g., drawing strong conclusions from
single studies), file-drawer effect (for
meta-studies), deliberate fraud, errors in
calibration, inadequate randomization procedures, software errors, and
various kinds of statistical errors. If any of the above occur, it is
possible that the data would indicate performance at significantly greater
than expected by chance and would make it appear as if there had been a transfer
of information when there had not been any such transfer. It is also
possible that information is being transferred, but not telepathically,
through sensory leakage. Or, maybe some people have an ability to
subconsciously recognize hidden patterns.

There are other scientific approaches to guessing
experiments that don’t presume deviation from chance implies something
paranormal. For example, the research of Peter Brugger and Kirsten Taylor
(2003) looks at guessing experiments from a neuroscientific perspective.
Brugger, a neuropsychologist at University Hospital, Zurich, and Taylor, a
postdoc in experimental psychology at Cambridge University, have argued that
the data in many ESP experiments that have found some people do
significantly better than chance at guessing such things as card or die
faces in allegedly randomized trials may indicate that some people have an
ability to subconsciously recognize hidden patterns. Such ability would not
require anything paranormal to explain. Brugger has received a grant to
study “implicit sequence learning,” as this alleged subconscious ability is
called. The Cogito Foundation, which is funding the study, has required that
a parapsychologist also be involved. John Palmer, current research director
of the Rhine Research Center, will be spending about a year in Zurich to
conduct the research with Brugger. (Personal correspondence.)

Brugger and Taylor don't explore this, but it is possible that
implicit sequence learning explains why Rupert Sheldrake was able to get
statistically significant results in his study on staring that showed that
some people can tell when others are staring at them. According to
Marks and
Colwell (2000), the study was flawed because it used a "random" process that
had a distinct pattern. The results were replicated only when the same
random process was used. But when a truly random process was used,
Sheldrake’s results couldn't be replicated by Marks and Colwell.

Brugger and Taylor suggest that the
letters ESP might better refer to Effect of Subjective Probability than to
extrasensory perception (2003). In other words, they propose that the data
from guessing studies might really indicate that some people have an ability
that others don’t, but that this ability involves processes understandable
by current scientific theories and knowledge.

Scientists like Peter Brugger are trying to find physiological bases for
alleged paranormal experiences. For example, he and his associates have
published reports on studies that examine a physical basis for such
experiences as hauntings, the out-of-body experience,
the feeling of a presence, the doppelganger experience, and phantom limb
sensations. One of the experiments that he and Palmer plan to do will
involve giving an experimental group L-dopa, which will increase levels of
dopamine in the brain. They want to investigate the influence of dopamine on
implicit sequence learning, guessing accuracy, and the reactions to
feedback. Brugger’s research indicates that “Dopamine seems to help people
see patterns,” (2002:
New Scientist). People with high levels of dopamine are more
likely to find significance in coincidences and pick out meaning and
patterns where there are none. He thinks that brain chemistry might account
for many paranormal experiences even in the absence of external stimuli.

There are other alternative explanations, as well, though
some of them seem farfetched. For example, it is possible that statistically
significant deviation from chance in psi experiments is caused by
Zeus, aliens, angels,
ghosts, Jehovah, jinn, or any one of a
number of beings who dwell in other dimensions. These beings may be
playing with parapsychologists, as James Alcock suggested with the Zeus
hypothesis. Or they may be unwitting conduits of data transfer. Perhaps
dolphins are picking up information telepathically from aliens and relaying it to
subjects in psi experiments. As I said, some of these alternative notions
are pretty farfetched, but they are possible nonetheless, and, in my view,
just as viable as the psi hypothesis.

We should also note that the notion of
statistical
significance itself is an arbitrary concept and carries with it no
necessary connection with our ordinary notion of importance.
Statistical significance only tells us the probability that a given
statistic is not spurious or due to a statistical accident. Statisticians
express the likelihood that a statistic is due to pure accident by referring
to its P-value. For example, P<0.01 means that there is a one percent
chance the stat is accidental. The most commonly used P-value in the social
sciences and medical studies is P<0.05, where there is a one in twenty
chance that the result was a statistical fluke. This standard can be traced
back to the 1930s and R. A.
Fisher. At that time, the number of data points that might be produced
by a scientific study would have been counted in the hundreds, thousands, or
tens of thousands. Today, some psi studies have more than ten million
data points. Should we assume that a statistical formula that was developed
rather arbitrarily for studies with much smaller quantities of data can be
applied without modification for studies with millions of data points?

Parapsychology is not alone in worshipping at the altar
of P<0.05, but it is the only science that concerns us here. A good example of mistaking statistical significance
for actual
importance was provided by Dean Radin and Roger Nelson in their assessment
of the data collected by Robert Jahn, Nelson, and Brenda Dunne in the
PEAR experiments on psychokinesis. The experiments
consisted of subjects who tried to use their minds to affect machines. In
over 14 million trials by 33 subjects over a seven-year period they found
that their subjects performed at the 50.02% level when 50.00% was expected
by chance. With such a large number of trials, this data plugs into some
statistical significance formula and spits out the result that the odds
against this happening by accident were beyond a trillion to one (Radin
1997: 140). Why am I not impressed?

conclusion

So, when confronted with data that indicate subjects in psi
experiments are performing at levels significantly greater than chance, why
should we conclude that psi is at work? We shouldn't, unless we can exclude
all other possibilities. Of course, we can never do this with absolute
certainly. But unless we can demonstrate that it is highly probable that all
other possibilities are false, we are not justified in concluding that psi
is the correct explanation for the data.

Some of the possibilities can be excluded on the grounds
that they are too farfetched to be taken seriously. For example, the
likelihood that Zeus, Jehova, dolphins, angels, ghosts, jinni, or aliens are
the cause of the data strikes me as rather beyond belief. However, what I
consider to be beyond belief should be irrelevant to the testing of any
hypothesis. Therefore, even these wild notions should probably be considered
by the parapsychologist if he or she is to be thorough in the investigation.

Other possibilities don't strike me as farfetched simply
because we have ample evidence that they have occurred on numbers of
occasions. We have numerous examples of cheating by subjects, fraud by
scientific investigators, sloppy controls, inadequate protocols, poor record
keeping, file-drawer effects, drawing grand conclusions from single or small
studies, misusing statistics, and the like. Furthermore, these examples are
not limited to parapsychologists, but can be found in all the sciences.

How many clear, decisive, unambiguous examples of psychic
ability do we have? So far, we have none.

Hence, it seems that there is little or no justification for
assuming that deviation from chance in a psi experiment is evidence of
anything anomalous or paranormal.